android: Introduce PlatformFrameBufferAllocator

The existing FrameBufferAllocator is not allowed to allocate a
new buffer while Camera is running. This introduces
PlatformFrameBufferAllocator. It allocates FrameBuffer using
cros::CameraBufferManager on ChromeOS and gralloc on non ChromeOS
platform. The allocated FrameBuffer owns the underlying buffer
but must be destroyed before PlatformFrameBufferAllocator is
destroyed.

Signed-off-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/android/mm/cros_frame_buffer_allocator.cpp

@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * cros_frame_buffer.cpp - Allocate FrameBuffer for Chromium OS using
+ * CameraBufferManager
+ */
+
+#include <memory>
+#include <vector>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/shared_fd.h>
+
+#include "libcamera/internal/framebuffer.h"
+
+#include "../camera_device.h"
+#include "../frame_buffer_allocator.h"
+#include "cros-camera/camera_buffer_manager.h"
+
+using namespace libcamera;
+
+LOG_DECLARE_CATEGORY(HAL)
+
+namespace {
+class CrosFrameBufferData : public FrameBuffer::Private
+{
+	LIBCAMERA_DECLARE_PUBLIC(FrameBuffer)
+
+public:
+	CrosFrameBufferData(cros::ScopedBufferHandle scopedHandle)
+		: FrameBuffer::Private(), scopedHandle_(std::move(scopedHandle))
+	{
+	}
+
+private:
+	cros::ScopedBufferHandle scopedHandle_;
+};
+} /* namespace */
+
+class PlatformFrameBufferAllocator::Private : public Extensible::Private
+{
+	LIBCAMERA_DECLARE_PUBLIC(PlatformFrameBufferAllocator)
+
+public:
+	Private([[maybe_unused]] CameraDevice *const cameraDevice)
+	{
+	}
+
+	std::unique_ptr<libcamera::FrameBuffer>
+	allocate(int halPixelFormat, const libcamera::Size &size, uint32_t usage);
+};
+
+std::unique_ptr<libcamera::FrameBuffer>
+PlatformFrameBufferAllocator::Private::allocate(int halPixelFormat,
+						const libcamera::Size &size,
+						uint32_t usage)
+{
+	cros::ScopedBufferHandle scopedHandle =
+		cros::CameraBufferManager::AllocateScopedBuffer(
+			size.width, size.height, halPixelFormat, usage);
+	if (!scopedHandle) {
+		LOG(HAL, Error) << "Failed to allocate buffer handle";
+		return nullptr;
+	}
+
+	buffer_handle_t handle = *scopedHandle;
+	SharedFD fd{ handle->data[0] };
+	if (!fd.isValid()) {
+		LOG(HAL, Fatal) << "Invalid fd";
+		return nullptr;
+	}
+
+	/* This code assumes all the planes are located in the same buffer. */
+	const size_t numPlanes = cros::CameraBufferManager::GetNumPlanes(handle);
+	std::vector<FrameBuffer::Plane> planes(numPlanes);
+	for (auto [i, plane] : utils::enumerate(planes)) {
+		plane.fd = fd;
+		plane.offset = cros::CameraBufferManager::GetPlaneOffset(handle, i);
+		plane.length = cros::CameraBufferManager::GetPlaneSize(handle, i);
+	}
+
+	return std::make_unique<FrameBuffer>(
+		std::make_unique<CrosFrameBufferData>(std::move(scopedHandle)),
+		planes);
+}
+
+PUBLIC_FRAME_BUFFER_ALLOCATOR_IMPLEMENTATION